A composite assembly comprises a first composite wall, a second composite wall spaced radially inward from the first outer wall, and a composite reinforcement ring attached to an outer surface of the second composite wall. The system comprises a server and a plurality of broadcasting device. The estimation unit is used for estimating a signal receiving strength of each of multiple transmission positions, compared with a signal transmission strength of each of one or more possible transmission positions of a first-type node of a to-be-test communications system on a transmission resource block. rotatably, coupled to each other via one or more conductive bearings.